Introducing: The New Engine That Could Increase Fuel Economy By Half

By Blake Z. Rong | May 22, 2012
The headline up there is the sort that blogs just love to scream. But hyperbole aside, if Delphi's experiments with new engine technology could come to fruition, our cars could see 50 percent greater fuel economy than today, without alternative fuels or batteries. What is Delphi working on? The automotive supplier is developing a gasoline engine that combines elements of a diesel powerplant with a gasoline engine. It's a single-piston test engine that uses compression ignition, as found on diesels: air is compressed to a temperature so hot that when fuel is injected, it ignites without a spark. Delphi calls this gasoline-direct-injection compression ignition. This sort of technology has been researched before, but engine developments simply haven't caught up. Things are different now. The high-pressure direct injection technology needed for this type of engine is now commonplace, and Delphi supplies gasoline direct injection systems to a variety of companies. If gasoline is injected into the combustion chamber in three precise bursts, Delphi researchers could monitor the exact moment when the fuel burns—which allows them to get the most out of the amount of fuel they use. What could this mean for the automotive realm? The new engine would get the same mileage as a hybrid, but cost less. It would be easier and cheaper to build, and use fewer resources. It would be the best of both gasoline and diesel worlds,  combining the 40 percent greater fuel efficiency of a diesel, but the relative environmental cleanliness of a gasoline engine. High efficiency, low emissions—with the trusty internal combustion engine always evolving at a rapid pace, it's only a matter of time before we see the fruits of Delphi's labor. Source: Technology Review

The difficulty has always been figuring out a way to lubricate the pintle in the injector. Gasoline is notoriously poor as a lubricant. No lubrication = too much heat = injector failure. Another problem with high pressure gasoline is that it is explosive if there is any air (oxygen) in the fuel supply -- like it begins to run out of fuel, sucks some air that hits a hot pump or injector pintle and the explosion happens in the wrong place at the wrong time. Not good. Diesel is it's own lubricant and requires a much larger quantity of air for combustion.